I came through the stroke fine because I went to the hospital right away and have been on warfarin ever since. My question is: If there’s no shunt, is the hole present?

A: The heart defect (or hole) responsible for a stroke is usually located in the top chambers of the heart, or atria. Diagnostic tests may detect an atrial septal defect (ASD) or a patent foramen ovale (PFO), both of which are “holes” in the tissue separating the right and left atria. A “shunt” is the term used to describe blood flow across such a defect. In your case, the concern is a right-to-left shunt, meaning that a blood clot could travel from the right to the left side of the heart, and then on to the brain and cause a stroke. Even if testing did not show a right-to-left shunt, it could still happen on occasion, such as after coughing or sneezing. Ask your cardiologist whether you indeed do or do not have a shunt. Treatments include closing the shunt via a device implanted during a heart catheterization (rather than open-heart surgery) or lifelong anti-coagulation with warfarin.

Heart Defect Often Causes No Symptoms The Saturday Evening Post